1. Technical Field
The present invention belongs to the technical field of hydraulic coke cutting of delayed coking units in the petroleum refining industry, and in particular, to a top drive mechanism for a drill rod.
2. Related Art
Delayed coking is a petroleum processing technology, and takes heavy oil as the raw material, which is rapidly heated to a coking reaction temperature through a heating furnace, and enters into a coke tower for a coking reaction. The heavy oil is subject to deep thermal cracking and condensation reactions; the produced gas, gasoline, diesel and gas oil pass through a pipeline to reach a downstream device and are processed in the downstream device, and the produced hundreds of tons of coke are left in the coke tower. The coke in the coke tower is gradually cooled to below 120° C. with steam and water; upper and lower seal bonnets of the coke tower are then opened, and a hydraulic coke remover is used to clean the coke in the coke tower; the upper and lower seal bonnets of the coke tower are then closed, and the process proceeds to a next production cycle: oil feeding, reaction, cooling, decoking, and so on.
The hydraulic coke remover usually includes: a decoking pump, a valve, a hose, a drill rod top drive, a drill rod, a coke remover, a winch, a pulley, and other devices. The decoking pump generates decoking water having certain energy, which passes through the valve, the hose, the drill rod top drive, and the drill rod into the coke remover, and is finally ejected from a nozzle of the coke remover. The coke remover has two groups of nozzles, i.e., drilling nozzles and cutting nozzles. Generally, when the hydraulic decoking begins, the drilling nozzle of the coke remover is used at first to eject the decoking water downward and drill a through hole with a diameter of about 1 m in the center of the coke tower, and the cutting nozzle of the coke remover is then used to eject decoking water toward two sides to gradually expand the channel; the coke is smashed in this process and flows out of the coke tower into a coke storage tank, and the decoking does not end until the coke in the coke tower is removed completely.
The drill rod top drive device is provided with a gooseneck connector and a high pressure hose. In decoking, the decoking water passes through the high pressure hose into a center channel on the top drive device and then passes through an output shaft of the drill rod top drive device into the drill rod and the coke remover. The output shaft of the drill rod top drive device is provided with a gear of a decelerator; the motor, after being decelerated by the gear, drives the output shaft to rotate the drill rod.
Currently, a threaded connection is employed between the output shaft of the drill rod top drive device for hydraulic decoking and the drill rod. During drilling, the coke sometimes may collapse and bury the coke remover, and removal of the coke remover requires repeated clockwise and counterclockwise rotation of the drill rod, so the threaded connection between the output shaft and the drill rod becomes unsuitable, and the threads are loosened easily; a lot of users use welding methods to prevent loosening, but this brings about difficulty when it is necessary to remove and replace the top drive or drill rod. Due to such reasons, the enterprises gradually use a flange connection, and the top drive device using a flange to connect a drill rod in the prior art mainly includes the following two structures: a. The employed output shaft structure is a stepped hollow shaft which is large in the middle and small at two ends, and the output shaft with such a structure has the following disadvantages: it is necessary to take apart the top drive device in installation, which not only is cumbersome but also is time-consuming and labor-consuming, and maintenance is very difficult; secondly, the axial force is unreasonable due to the supporting manner of the output shaft, rendering a high damage rate of the top drive device. b. A flange structure is disposed at a lower end of the output shaft, and the force is directly output to the flange structure through a power mechanism so as to drive the drill rod to rotate; as the supporting manner of the output shaft is also unreasonable, the output shaft is easily damaged, and the top drive device often needs to be maintained.